5'-Nucleotides as potential formulations for administering nucleoside analogs in man.

A variety of nucleoside analogs have shown carcinostatic activity. In some instances they are relatively rapidly excreted. In others they are relatively rapidly inactivated in vivo by catabolic enzymes. In both cases it appeared desirable to have nucleoside derivatives that would act as depot forms of the nucleoside analogs and would be converted in vivo to the respective nucleoside analog. Gish et al. (3) have synthesized a number of derivatives of arabinosylcytosine, a nucleoside with a very short half-life in vivo because of enzymatic deamination to arabinosyluracil (6). The same problem of rapid deamination pertained to ara-A3 (8). ara-6-MP represented an